Dispensers that utilize a pump dome valve are primarily configured to be used with collapsible containers. As is well understood in the art, a pump dome valve provides an elastomeric or flexible plastic material that is shaped as a pump dome that forms a pump dome cavity within the pump dome. When the pump dome is depressed a quantity of fluid material is dispensed. In other words, as the flexible material is depressed or actuated, the fluid material that is contained within the pump dome cavity is dispensed and as the pump dome is released and returns to its original shape, the suction forces generated by the pump dome draw the material from within the container into the pump dome cavity for the next actuation of the pump dome. Such pump dome valves are used with containers that have a collapsible structure such as a plastic bag. As the pump dome is repeatedly actuated and fluid material is drawn from the container into the pump dome cavity, the build-up of vacuum forces causes the container to collapse. Since the container is collapsible, the vacuum forces generated do not hinder the dispensing of material. However, such pump dome valves are problematic in that they require many component pieces to construct the valve. These component pieces may include spring-loaded check valves, specially oriented fittings, and a retaining ring to hold the pump dome. These pieces are costly and allow for more mechanical interconnections to fail, thus rendering the pump dome valve inoperative. Moreover, such valves cannot be used on non-collapsible/rigid refill containers, as the vacuum forces within the container cannot be overcome to allow for the material to be dispensed.
One solution for overcoming the inability to use a pump dome valve with non-collapsible refill containers is to allow for a separate venting feature to be associated with the refill container. As such, when a vacuum develops within the rigid refill container, the vacuum force pulls in ambient air through a vent in the refill container, not the pump dome valve, thus allowing air to enter the refill container and relieve the vacuum forces. As a result, the fluid material may continue to be dispensed upon actuation of the pump dome valve. However, such a configuration still requires a vented container or valve and the problematic features of the aforementioned pump dome valves.
Accordingly, there is a need in the art for a simplified pump dome valve structure which allows for venting of the pump dome valve so as to eliminate the multiple pieces/parts of the prior art valve constructions, eliminate the separate venting of the rigid refill container, and to reduce the number of mechanical interconnections required for the valve.